beneath the table to the abstract. Use the Word Count cmd under Utilites menu for counting Significance HIV transmission to infants by breast feeding after maternally acquired anti-HIV antibodies decline is well documented. Neonatal vaccination may reduce HIV transmission to children in developing nations where safe alternatives to breast feeding are not available. Immunization with plasmid DNA encoding HIV proteins has been proposed as a safe, stable, and economical anti-HIV vaccine. However, a neonatal anti-HIV vaccine must also elicit immunity in the presence of maternal HIV antibodies. Objectives Infection of newborn rhesus macaques with simian immunodeficiency virus is a well-established model for pediatric HIV infection and AIDS. This study evaluated whether non-replicating plasmid DNA encoding theSIVmac239 envelope gene could elicit SIV-specific immunity in neonates that have or that lack transplacentally acquired SIV antibodies. Results Nine pregnant female rhesus macaques were used; three animals were immunized with whole-inactivated SIV in adjuvant. Vaccinated dams transferred SIV-specific serum antibodies to their infants (Group A). Six neonates of unvaccinated dams had no SIV antibodies (Group B). All nine infants were inoculated intramuscularly with SIV env DNA (at birth and again at 4 months of age). All infants were healthy throughout the study period of 7 months. Assays of SIV-specific antibodies and CD4+ lymphocyte proliferation are underway. Thus, we will determine whether transplacentally acquired SIV antibodies can interfere with immune responses elicited by SIV DNA inoculation of rhesus neonates. Results from these experiments will be important in evaluating whether an HIV DNA vaccine would be safe and immunogenic in human newborns and might be used to protect human infants with maternally-derived HIV antibodies against HIV exposure by breast milk. Future Directions At 1 year of age each of the nine animals vaccinated with SIV env DNA will be inoculated orally with SIVmac239 to determine whether neonatal vaccination can provide long-term protection against virulent SIV. KEY WORDS pediatric simian AIDS, oral SIV transmission, perinatal HIV transmission, neonatal immunization, live-attenuated vaccine FUNDING NIH Grants RR00169 and AI039109, E. Glaser Pediatric AIDS Foundation Scientist Award 8-97